The act of being very relaxed in a social setting. A derivative of Spanish word "tranquilo". Universal term.
Example. (Spanish) - "Esta noche me voy para la casa de mi novia, con una botella de vino, ollendo una musikita. Un tranqui."
translation in English - "Tonight, I'm going to my girl's house, with a nice bottle of wine, some music in the back ground. Un tranqui."